ax25: fix warning in net/ax25/sysctl_net_ax25.c

fix this warning:

  net/ax25/sysctl_net_ax25.c:27: warning: ‘min_ds_timeout’ defined but not used
  net/ax25/sysctl_net_ax25.c:27: warning: ‘max_ds_timeout’ defined but not used

These are only used in the CONFIG_AX25_DAMA_SLAVE case.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ax25/sysctl_net_ax25.c

@@ -24,7 +24,9 @@ static int min_idle[1],			max_idle[] = {65535000};
 static int min_n2[] = {1},		max_n2[] = {31};
 static int min_paclen[] = {1},		max_paclen[] = {512};
 static int min_proto[1],		max_proto[] = { AX25_PROTO_MAX };
+#ifdef CONFIG_AX25_DAMA_SLAVE
 static int min_ds_timeout[1],		max_ds_timeout[] = {65535000};
+#endif
 
 static struct ctl_table_header *ax25_table_header;